In Korea in which most of energy sources are dependent on imports, in an aspect of national security or to maintain a continuous economic growth, it is necessary to establish a long-term energy source supply policy capable of maximally reducing a level of dependence on energy imports and to develop fundamental clean alternative energy.
In this reality, biomass is being regarded as one field of alternative energy capable of easing concerns of exhaustion of fossil fuel and environmental pollution.
Biomass is a term which refers to biological organisms including plant bodies generated by photosynthesis of microorganisms and plants which receive solar energy, fungus bodies, and animal bodies which live on the same. Accordingly, biomass resources have a comprehensive meaning which includes farinaceous resources such as grains, cellulosic resources including forest trees and agricultural by-products such as rice straws and rice husks, saccharic resources such as sugar canes and sugar beets, and organic waste such as food waste and the like.
Currently, biomass having a dry weight of about 1.8 to 2 trillion tons is present on the earth, biomass of 200 billion tons corresponding to about 10% of the amount is annually produced, which corresponds to about 0.1% of solar energy beating down on the earth and accumulated as biomass. Also, since biomass basically has zero environmental effect caused by CO2, biomass is an attractive energy source in comparison to fossil fuel.
Meanwhile, conventional generation systems may be classified largely into a method using fossil fuel and a method using biomass as new renewable energy.
A conventional generation system using fossil fuel needs additional post-treatment equipment for treating a large amount of heavy metal and sulfur compounds included in the fuel such that the equipment and apparatus are enlarged. Also, since there is a limitation in miniaturizing a generation system, generation systems have been developed in the unit of plant. Even in an economic aspect, since secondary pollutants such as tar and waste water are generated in post-treatment equipment of a generation system, huge operating costs are necessary for reprocessing the secondary pollutants. Nonetheless, due to tightening of international environmental regulations, it is expected that costs for adding and operating carbon dioxide reducing equipment increase. Also, since supply and costs for raw materials fluctuate according to external factors such as international politics, economic situations, and the like, disturbance in costs for operation is caused such that it is basically difficult to make a stable profit.
To solve the above-problems of conventional generation systems using fossil fuel, generation systems using biomass such as waste and the like have been suggested. A biomass generation system includes a gasification process of generating a synthesis gas which includes less tar and dust by thermally decomposing biomass such as domestic waste, food waste, and the like and generation equipment configured to generate power using the synthesis gas. Here, not only the gasification process needs investment costs for large-scaled equipment for purifying the synthesis gas and but also more energy loss occurs than when combustion heat of biomass is directly utilized. Also, since types of waste usable as biomass are limited, additional input of workers for classification of collected wastes is considerable. Since additional post-treatment equipment for removing harmful substances in the waste is needed like conventional generation systems using fossil fuel, it is difficult to fundamentally decrease a size of an apparatus and to reduce maintenance costs.
Small generation systems adequate for domestic use among conventional generation systems are generally used for heating and hot water supply and may be classified into a cogeneration method of petroleum/gas boilers and a heat source supply method of wood pellet boilers. The above conventional small generation systems have an advantage of simultaneously performing hot water supply and power generation but have a problem in which an excessive heat source is consumed for producing hot water such that electricity generation efficiency is significantly lower than that of large generation systems. Also, since large amounts of impurities and chemical composition are included in wood pellets used as a raw material, when wood pellets are burned, a secondary pollution source is generated. When high-quality wood pellets having fewer impurities are used to solve this, economic feasibility is significantly decreased and there is a difficulty in practical application.